Create Azure Image and Azure Gallery Image from snapshot

Currently we create Azure Image and Azure Gallery Image by uploading to a storage. This is somewhat inconvenient, as storages need global unique names and are bad to verify if there is still data in them.

Both Azure Image and Azure Gallery Image can be created from a snapshot (Image, Gallery Image). Snapshots can be written from the outside (Snapshot Grant Access). Snapshots are also namespaced and simple visible objects.

Creating those types from a snapshot instead on a blob will make the config easier, as no (global unique) storage is required.